A switching power converter comprises an energy storage element such as an inductor and a set of switching elements that selectively couple the energy storage element between an input and output. A controller operates the switching elements such that a regulated output voltage is supplied. There are various well known types of switching regulators. For example, a buck converter steps down an input voltage to a lower output voltage, a boost converter steps up an input voltage to a higher output voltage, and a buck-boost converter can either step up or step down the input voltage to provide the desired output voltage.
It is desired for a switching converter to have good stability and transient response. It is known to address this by accurately sensing the inductor current.
Sensing from an inductor input node (SW node) can get accurate inductor current information. However, doing this is costly and complex for high-voltage converters.
Besides, the inductor input node cannot reflect the instant change on the output voltage so this technique cannot provide fast transient response.
The inductor current may also be sensed from the inductor output node. This has a lower cost associated with it and provides good transient response, but one cannot get accurate inductor current information when different external components are used.
Sensing from both the inductor input and output nodes is also possible and provides a responsive solution, but it is still difficult to sense under high-voltage applications.
All of these existing approaches suffer from poor ground noise rejection.